A foot bump. What might this be, and mean?

A foot bump.
We see this kind of thing all the time. This is a fixed pes planus (flat foot). When we dorsiflex the big toe, the arch does not go up as you see in the photo. That is passive dorsiflexion, if the arch does not go up passively, there is no way you are actively going to achieve this. And, using an orthotic to "attempt" to raise this arch is not only pointless, but it is futile and it will likely cause them pain. This arch does not rise, no matter how hard you put up into it. The bump, that is the navicular bone, and its associated arthritic build up at the adjacent joints, and likely soft tissue accomodation/hypertrophy. You can't needle, ultrasound, tape, adjust or rub this bump away, so stop wasting your and your patient's time selling them that wasteful thinking. It ain't gonna happen.
This is what happens when someone earns a collapsed longitidinal arch, the 1st metatarsal no longer plantarflexes (arch up) and it becomes fixed in dorsiflexion, thus affecting the mechanics at the proximal aspect of the 1st ray complex (navicular-cuneiform-met intervals).
Why? This happened because this client has significantly compromised ankle mortise dorsiflexion, and they chose to find it at the next joint complex distally, as mentioned above. So, they are finding pseudo-ankle rocker at arch collapse? Yes, we discuss this often, more pronation will advance the tibia forward. It is not desirable, but moving forward has to occur, and some people have no choice but to find it from excessive internal rotation and pronation of the limb. And this is what happens when it happens over years. Now the deformity is painful itself in the shoe, it is a new set of problems for this client.
Can this problem occur in reverse ? Yes, a loss of hallux dorsiflexion can afford the same end result.
We have a rule, at the very VERY least, check the joint above and below the area of problem/symptom. Often you will find another piece of the puzzle causing your client's pain.

Pronation Primer: Part 2

The problem with OVERPRONATION

The consequence of under or over pronation ultimately means other articulations, including the spine, will have to attenuate more shock. Over time, this may lead to articular cartilage degeneration, disc degeneration, or ligamentous laxity, due to repetitive stresses.

What about assymetrical pronation?

It is rare that people over or under pronate the same amount on each side. Excess midfoot pronation on the right causes more internal rotation at the right knee (see above picture), and an increased valgus stress here. This puts the quadriceps at a mechanical disadvantage and stretches the adductor group, often making them stretch weak, and shortens the abductors, especially the gluteus medius, which often becomes short weak. The right foot, since it is now a poor lever, will often be externally rotated and toes claw, because the center of gravity has moved medially and they are trying to make that limb stable to bear weight on so they can progress forward. They will often toe off from the inside of the great toe (as is often evidenced by a pinch callus here). The medial rotation of the lower leg causes internal rotation of the thigh and anterior nutation of the pelvis on that side, both which now put the gluteus maximus at a mechanical disadvantage, limiting hip extension on that side. Now the extension has to occur to somewhere, so it often occurs in the lumbar spine, along with rotation and lateral bending to that side, increasing compression on the right facets. Now the vestibular system kicks in to right the head and we get contraction of the left paraspinals. Arm swing usually increases on the contralateral side to assist in propulsion forward. What effect do you think THAT has for about 10 thousand steps a day on spinal mechanics? What effect are we having on the nervous system and what neuroplastic changes are occurring? Hmmmm….

Having both feet planted on solid ground, or rather having both feet planted solidly on the ground should concern you. As you can see, knowing about pronation and its effects on the entire kinetic chain is paramount to the clinician. The effects reach far beyond the foot and can often be the root of recurrent biomechanical faults in the human frame.

And some people thought it was as easy as slipping an orthotic in there…

Yup, we still are….The Gait Guys

Pronation Primer: Part 1

A lot of folks seem to be on a mission to eliminate pronation, calling it the scourge of humanity and source of human ailment. While we agree that overpronation causes biomechanical faults in the lower kinetic chain, so does under pronation, and some pronation is necessary and required for normal locomotion. We hope this post serves to clarify any misconceptions there may be about it.

When most people think of pronation, they think of midfoot pronation, or pronation about the subtalar or transverse tarsal joints. Pronation can actually occur about any articulation or bone, but with respect to the foot, we like to think of rearfoot (ie. talo-calcaneal), midfoot (talo-navicular) and forefoot (transverse tarsal). The question is why does this matter?

Pronation, with respect to the foot, is defined as a combination of eversion, abduction and dorsiflexion  (see picture attached) which results in flattening of the planter vault encompassing the medial and lateral longitudinal arches. In a normal gait cycle, this begins at initial contact (heel strike) and terminates at midstance, lasting no more than 25% of the gait cycle.

In a perfect biomechanical world, shortly following initial contact with the ground, the calcaneus should evert 4-8 degrees, largely because the body of the calcaneus is lateral to the longitudinal axis of the tibia. This results in plantar flexion, adduction and eversion of the talus on the calcaneus, as it slides anteriorly. At this point, there should be dorsiflexion of the transverse tarsal (calcaneo-cuboid and talo-navicular joints). Due to the tight fit of the ankle mortise and its unique shape, the tibial rotates internally (medially). This translates up the kinetic chain and causes internal rotation of the femur, which causes subsequent nutation of the pelvis and extension of the lumbar spine. (Hmm, this is beginning to sound like a common cause of low back pain) This should occur in the lower kinetic chain through the 1^st half of stance phase. The sequence should reverse after the midpoint of midstance, causing supination and creating a rigid lever for forward propulsion.

Pronation, along with knee and hip flexion, allow for shock absorption during throughout the 1^st half of stance phase. Pronation allows for the calcaneo-cuboid and talo-navicular joint axes to be parallel making the foot into a mobile adaptor so it can contour to irregular surfaces, like our hunter gatherer forefathers used to walk on before we paved the planet. Problems arise when the foot either under pronates (7 degrees valgus results in internal tibial rotation), resulting in poor shock absorption or over pronates (> 8 degrees or remains in pronation for greater than  50% of stance phase).

Wow, kind of overwhelming, eh? Stay tuned for part 2 tomorrow.

We remain….The Gait Guys…Telling it like it is…..